Apparatus and method for applying coatings



H. A. BALL APPARATUS AND METHOD FOR APPLYING COATINGS Fil d June 9, 1955' June 2, 1959 4 Sheets-Sheet 1 INVENTOR Haw) A 5/1 ATTORNEY APPARATUS AND METHOD FOR APPLYING COATINGS Filed June 9, 1955 4 Sheets-Sheet 2 u ixm Fig. .ZZT

I INVENTOR BY WM 4.

ATTORNEY June 2, 1959 H. A. BALL APPARATUS AND METHOD FOR APPLYING COATINGS Filed June 9, 1955 4 Sheets-Sheet 3 FI I INVENTOR ATTORNEY June 2, 1959 H. A. BALL 2,889,237

APPARATUS AND METHOD FOR APPLYING commas Filed June 9, 1955 4 Sheets-Sheet 4 INVENTOR flEA/Ry A. 5444 BY 47:24am [2 ATTORNEY APPARATUS AND METHOD FOR APPLYING COATINGS Henry A. Ball, Glenshaw, Pa., assignor to The 'Cleanola Company, Glenshaw, Pa., a corporation of Pennsylvanla Application June 9, 1955, Serial No. 514,255

Claims. (Cl. 117-94) This invention pertains to annular coating apparatus and to the method of applying coating compositions to objects. More particularly this invention relates to the radial application to objects of thin fihn-forming coatmg compositions attenuated by a volatile carrying liquid and to the apparatus for effecting such an application without the use of air.

The apparatus and methods hitherto used. to make radial applications of coating composition to objects have fundamentally comprised flooding the coating composition on the object and mechanical wiping or air wiping the object to spread the coating composition and remove the excess, resulting in non-uniformity in the coating and waste of the coating composition. Under conditions where the excess coating composition has been collected and reused, the resultant contamination of the coating composition causes variation in the quality of the coating and ultimately renders the coating composition unusable. In most instances the coating apparatus in prior use required complete enclosure by a tank or shield to accomplish the purpose of collecting the excess coating material, thereby rendering the adjustment diflicult and the apparatus unwieldy.

Therefore, one object of this invention is to provide a means of radially applying a thin uniform coating to objects with the speed required in production line methods. A further object of this invention is to eliminate the necessity for wiping the object after the application of the coating. A further object of this invention is to reduce waste or loss of the coating composition to a minimal amount. A still further object of this invention is to eliminate the excess air from the coating composition and to reduce premature oxidation thereby. Further and additional objects will appear from thefollowing description and the appended claims.

Briefly to describe the primary features of a coating apparatus embodying my invention, I provide a sectional annular housing having annular ducts or chambers therein which communicate with a plurality of radial nozzles circumferentially spaced in the inner periphery thereof; the said radial nozzles being slanted or inclined to the axis of the said annular housing. The restricted condition of the orifice of the said radial nozzles is such that when the attenuated coating composition is projected therefrom under the influence of heat-reduced viscosity and mechanical pressure it is resolved by the abrupt release of the said pressure into a propelled free cloud having roughly the shape of a cone comprising the several free clouds of coating composition issuing from the said inclined radial nozzles and converging on the projected center of the said coating annulus. Relative movement between the object to be coated and the said annular housing encircling the said object causes the said object to intersect the propelled free cloud of coating composition and the film-forming content thereof adheres to the said object.

Fig. I is an elevational view of one form of my coating annulus.

Fig. II is a cross-sectional view through the coating annulus shown in Fig. I and taken in the plane of section line II-II of Fig. I. V

Fig. III is a cross-sectional view through the coating annulus shown in Fig. I and taken in the plane of section line IlI-III of Fig. I.

Fig. IV is a fragmentary cross-sectional View through a modified form of my coating annulus, the part not shown being identical with Fig. II.

Fig. V isan elevational view of a modified form of my coating annulus.

Fig. VI is a cross-sectional view through the coating annulus shown in Fig. V and taken in the plane of sec tion line VI- -VI of Fig. V.

Fig. VII is a non-detailed elevational view of the coating annulus shown in Fig. I and showing the propelled free cloud of coating composition and the work being coated.

Fig. VIII is a non-detailed cross-sectional view through the coating annulus taken in the plane of section line VIII-VIII of Fig. VII and showing the propelled free cloud of coating composition without the work in position for coating to demonstrate more clearly the blanket ing effect of the said free cloud. i

Referring to Figs. I, II, HI and IV, the numeral 1 indicates an inlet for the coating composition from the supply system into the coating annulus which communicates with an annular circulating duct or chamber 2. Receptacles 3 intersect the said annular circulating duct 2 and recessed therein are shut-off valve seats 4 which cooperate with mechanical means (not shown on the drawings but preferably automatic in operation) for which the threaded receptacles 5 are provided, to interrupt the flow of coating composition when the coating annulus is not in operation. When the said shut-off valve seats 4 are open they connect the annular circulating duct 2 with an annular distributive duct 6 which communicates with holes 7 circumferentially spaced to con nect with nozzle assemblies 8 recessed in the beveled portion of the inner periphery of the said coating an nulus. An outlet 9 adjacent to the inlet 1 communicates 'with the annular circulating duct 2 to conduct'the coating composition back into the supply system for the re-application of heat which produces the reduced 'vis cosity. Rings 10 and 11 are held together by circumferentially spaced screws 12 and this combination is secured to ring 13 by means of circumferentially spaced screws 14. Extenders 15 (shown only in Fig. IV) are installed only to provide an economical adaptation of a large diameter coating annulus to the coating of small objects.

Referring now to Figs. V and VI, numeral 16 indi cates an inlet for the coating composition from the supply system into the outer ring 17 of the coating annulus which communicates with an annular duct or chamber 18. Holes 19 in circumferentially spaced relation in the intermediate ring 20 connect the annular duct 18 with an additional annular duct or chamber 21. Holes 22 in circumferentially spaced relation in the inner ring 23 connect the annular duct 21 with the inclined radial nozzle assemblies 24 recessed in the beveled portion of the inner periphery of the said coating annulus. The packings 25, 26, 27 and 28 which eliminates leakage between the rings is secured and expanded by closure strips 29, 30, 31 and 32 which are fastened to the various rings by means of circumferentially spaced screws 33, 34, 35, 36 and 37.

In Fig. VII the letter A indicates the coating composition issuing from the circumferentially spaced inclined nozzles of the coating annulus and resolved into the condition of a propelled free cloud by the abrupt release of the mechanical pressure by which it was influenced in the coating annulus and the supply system. The letter B indicates the work being coated as the relative movement between the work and the coating annulus positions the said work for the adherence thereto of the film-forming material comprised in the said free cloud of coating composition.

In Fig. VIII the letter A indicates the coating composition issuing from the circumferentially spaced inclined nozzles of the coating annulus and resolved into the condition of a propelled free cloud by the abrupt release of the mechanical pressure by which it was influenced in the coating annulus and the supply system, the work to be coated being eliminated to demonstrate more clearly the blanketing eifect of the said free cloud.

The coating composition contemplated for the proper functioning of the coating annulus comprises a filmforming material attenuated by a volatile carrying liquid which is introduced from the supply system into the coating annulus at a temperature of from 100 to 200 F. and under mechanical pressure of from 300 to 500 pounds per square inch. The nozzle orifice is restricted in size so that in an order of heat-reduced viscosity and abrupt release of the mechanical pressure at the inward terminus of the said nozzle orifice the coating composition is resolved into the condition of a propelled free cloud thereby liberating a proportion of the volatile liquid comprised in the said coating composition while adhering to the said object the film-forming material which hardens and becomes heat stable upon application.

The said inclined radial nozzles are so arranged that each of the several free clouds of coating composition issuing from the said nozzles diverges from the point of issuance circumferentially to intersect the free clouds next adjacent, thereby producing an uninterrupted cloud zone of coating composition of larger diameter than the object being coated and having roughly the outline of two cones with their apexes on the projected center of the coating annulus. The apparatus embodying my invention is best adapted to the coating of elongated objects of circular cross-section such as rods, pipes and tubes, the propelled free cloud of coating composition aifording complete orbital coverage only within the inscribed circle circumferentailly connecting the points of intersection of the several free clouds of coating composition issuing from the radial nozzles and producing the cloud zone as shown in Fig. VII.

For the purpose of coating small objects with a large diameter coating annulus embodying my invention an economical adaptation is made by installing extenders as shown in Fig. IV or by blanking oflf certain of the nozzles or by using both adaptive methods so that the quantity of coating composition issuing from the nozzles is not excessive with relation to the surface being coated.

An important feature of the novelty of my invention is found in the flexibility of operation of the apparatus comprising widely variant combinations of inclined radial nozzles positioned in a singular structure with a singular source of supply to effect a simultaneous coating in a 360 orbit upon an object intersecting the annular blending zone formed by the conical shaped propelled free cloud of coating composition.

An additional important feature is found in the arrangement of the structure comprising shut-oil valves in close proximity to the nozzles thereby permitting the interruption of the coating operation at the completion of any stage in a production line without allowing the run out of any liquid coating composition contained in the annulus, at the same time permitting the continued circulation of the coating composition through the coating annulus and the supply system for the immediate resumption of operation. This arrangement of the shut-off mechanisms proximate to the nozzles provides sensitive, immediately effective means of controlling the operation of the annulus, and affords a continuously present supply of the heated coating composition under the influ- 4 ence of mechanical pressure for instant response to intermittent operation of the annulus without the loss of coating composition.

I have operated the apparatus embodying my invention successfully by applying a mechanical pressure of 400 pounds per square inch to the attenuated coating composition which was heated to F. Under these conditions the coating composition was resolved into a finely dispersed free cloud upon issuance from the nozzles having orifice .011 inch in diameter and no condensation of the coating composition into liquid droplets during passage from the nozzles to the work was observable. When elongated objects of circular crosssection were passed through my coating annulus and intersected the propelled free cloud of coating composition under these conditions at a speed of 300 feet per minute, the resultant coating on the objects was thin and uniform and the flow thereof was negligible.

To determine the quantitative disposition of the coating composition accomplished by the apparatus embodying my invention, operations were conducted using a coating composition comprising 50 per centum of film-forming solid material and 50 per centum of volatile carrying liquid by weight, the film-forming solid material comprising drying oils, dryer catalysts, and resins and the volatile carrying liquid comprising naphtha. This constituency resulted in a coating composition comprising 43 per centum of film-forming solid material and 57 per centum of volatile carrying liquid by volume. The quantity of coating composition so constituted which was used would have produced a wet coating on the object 2.32 mils thick if the entire amount projected had reached the object, however, actual measurement showed that the wet coating was only 1.70 mils thick, from which it is concluded that a very substantial proportion of the volatile carrying liquid comprised in the coating composition was liberated during passage from the nozzles to the object. The remainder of the volatile carrying liquid was liberated after adherence to the object resulting in a dry coating 1.00 mils thick.

Variations of the pressure, temperature, number of nozzles, speed of relative movement, and constituency of the coating composition may be made to effect a wide range of desired coating results.

Certain changes may be made in the arrangement set forth in the specifications and shown in the drawings, it being understood that modifications in the precise embodiment of the invention may be made within the scope of the following claims without departing from the spirit of the invention.

I claim:

1. A device for applying a thin film of coating material to an object, comprising an annular housing for encircling an object in non-engaging relation thereto, the said annular housing having inlets for coating material in the outer periphery, internal ducts including at least one annular distributive duct, and a plurality of inclined radial nozzles circumferentially spaced in the inner periphery of the said annular housing communicating with the said annular distributive duct and having orifice so restricted that under pressure delivery of the said coating material therefrom issuance tends to resolve the said coating material into the condition of a propelled free cloud.

2. A device for applying a thin film of coating material to an object, comprising an annular housing for encircling an object in non-engaging relation thereto, the said annular housing having inlets and outlets for coating material including at least one inlet and one outlet in the outer periphery, internal ducts including at least one annular circulating duct and one annular distributive duct, and a plurality of inclined radial nozzles circumferentially spaced in the inner periphery of the said annular housing communicating with the said annular distributive duct and having orifice so restricted that under pressure delivery of the said coating material therefrom issuance tends to resolve the said coating material into the condition of a propelled free cloud.

3. A device for applying a thin filrn of coating material to an object, comprising an annular housing for encircling an object in non-engaging relation thereto, the said annular housing having inlets and outlets for coating material including at least one inlet and one outlet in the outer periphery, internal ducts including at least one annular circulating duct and one annular distributive duct, shutoff valves between the said annular circulating duct and the said annular distributive duct and a plurality of inclined radial nozzles circumferentially spaced in the inner periphery of the said annular housing communicating with the said annular distributive duct and having orifice so restricted that under pressure delivery of the said coating material therefrom issuance tends to resolve the said coating material into the condition of a propelled free cloud.

4. The method of applying to an object a thin permanent coating film by encircling the said object with a plurality of inclined radial nozzles directed relatively inward and disposed in circumferential spaced relation to the said object, supplying to the said nozzles a coating composition under mechanical pressure and heated to a condition of reduced viscosity and comprising fihnforming substance and a volatile carrying liquid therefor, causing relative axial movement between the said nozzles concertedly acting and the said object, and projecting from the said nozzles against the said object the said coating composition under the influence of the said reduced viscosity and the said mechanical pressure and resolved 'by release of the said pressure into the condition of a plurality of propelled free clouds, the condition of the said free clouds of coating composition being such as to liberate a proportion of the volatile carrying liquid comprised in the said coating composition during passage from the said nozzles to the said object while adhering the film-forming content thereof to the said object.

5. The method of applying to an object a thin permanent coating film by encircling the said object with a plurality of inclined radial nozzles directed relatively inward and disposed in circumferential spaced relation to the said object, supplying to the said nozzles a coating composition under mechanical pressure and heated to a condition of reduced viscosity and comprising filmforming substance and a volatile carrying liquid therefor, causing relative axial movement between the said nozzles concertedly acting and the said object, projecting from each of the said nozzles against the said object the said coating composition under the influence of the said reduced viscosity and the said mechanical pressure and resolved by release of the said pressure into the condition of a plurality of propelled free clouds, and uniformly regulating the circumferential spaced relation of the said nozzles so that each of the said clouds of coating composition intersects the said clouds next adjacent to form a roughly conical shaped cloud zone spaced inwardly from the extremities of the said nozzles and having effective area greater than the said object, the condition of the said free clouds of coating composition being such as to liberate a proportion of the volatile carrying liquid comprised in the said coating composition during passage from the said nozzles to the said object while adhering the film-forming content thereof to the said object.

References Cited in the file of this patent UNITED STATES PATENTS 1,910,674 Bramsen May 23, 1933 1,914,850 Foster June 20, 1933 2,377,220 Focha May 29, 1945 2,410,626 Boudreau Nov. 5, 1946 2,670,240 Cunningham Feb. 23, 1954 2,755,067 Williston July 17, 1956 2,762,115 Gates Sept. 11, 1956 2,763,575 Bede Sept. 18, 1956 FOREIGN PATENTS 889,917 Germany Sept. 14, 1953 

4. THE METHOD OF APPLYING TO AN OBJECT A THIN PERMANENT COATING FILM BY ENCIRCLING THE SAID OBJECT WITH A PLURALITY OF INCLINED RADIAL NOZZLES DIRECTED RELATIVELY INWARD AND DISPOSED INCIRCUMFERENTIAL SPACED RELATION TO THE SAID OBJECT, SUPPLYING TO THE SAID NOZZLES A COATING COMPOSITION UNDER MECHANICAL PRESSURE AND HEATED TO A CONDITION OF REDUCED VISCOSITY AND COMPRISING FILMFORMING A SUBSTANCE AND A VOLATILE CARRYING LIQUID THEREFOR, CAUSING RELATIVE AXIAL MOVEMENT BETWEEN THE SAID NOZZLES CONCERTEDLY ACTING AND THE SAID OBJECT, AND PROJECTING FROM THE SAID NOZZLES AGAINST THE SAID OBJECT THE SAID COATING COMPOSITION UNDER THE INFLUENCE OF THE SAID REDUCED VISCOSITY AND THE SAID MECHANICAL PRESSURE AND RESOLVED BY RELEASE OF THE SAID PRESSURE INTO THE CONDI- 